If an Internet research session sends you down a rabbit hole, by the time you resurface you can be staring at dozens upon dozens of tabs open. To organize the messy results of your research, you may find it useful to manipulate groups of tabs. That is, move, close, pin, or bookmark multiple tabs in one fell swoop.
Chrome provides the ability to move and close multiple tabs natively, while Firefox extension Multiple Tab Handler provides this functionality and much more.
In Chrome, you can select multiple tabs by clicking on tabs while holding down the Ctrl key or select a range of tabs by holding down the Shift key and clicking. The tabs you selected are highlighted slightly and you can then drag to move the group to another spot in your current Chrome window, to the desktop to open the group in a new window, or to another window you have open. You can also use the right-click menu to close or pin the group of tabs.
It's great that such functionality is built in to Chrome, but there are a couple caveats. For one, you can highlight multiple tabs using the Command or Shift keys on a Mac but that's it -- you can't then move or close or pin your group of highlighted tabs. For another, you can manipulate multiple tabs in Windows 8 only when Chrome is desktop mode. When using Chrome in its default full-screen Windows 8 mode, such functionality doesn't exist.
To manipulate multiple tabs in Firefox, you will need to install an extension. Multiple Tab Handler provides the ability close, pin, move, and bookmark multiple tabs, among other actions, and it works with both Windows 8 and Mac OS X. As with Chrome natively, Multiple Tab Handler lets you use the Ctrl (or Command key) and the Shift key to select multiple tabs with Firefox. Selected tabs are boldly highlighted in blue, and you can drag your selected tabs to another spot in your current window, another existing window, or a new window. You can also use the right-click menu to reload, bookmark, duplicate, or pin the tabs or move them to a group. You can also close the selected tab or close all but the selected tabs.